<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>
<form action="#" method="post" autocomplete="off">
    <label for="username">用户名</label>
    <input id="username" name="username" value="" placeholder="请在此处输入用户名" required>
    <button type="submit">提交</button>
    <button type="reset">重置</button>
    <button type="button">按钮</button>
</form>

</body>
</html>